Improvement in alarm-locks



inih giant Letters Patent No. 112,987, dated March 21, 1871.

IMrRo'vEMl-:NT mi ALARMfLocKs.

The Schedule referred tov in these Letters Patent and making part of the' lama.

To all lwhom it may concern Beit known that I, JAMES ,HARRY THoRP, of

New York, in the county of 'New York and in the State'of NewYork, have invented certain new and useful Improvements in Alarm-Locks; and do hereby declare that the following isa full, clear, and exact description thereof, reference being had to the ac. companying drawing and to the'letters of reference marked thereon making a part 'of this specication.

The nature of my invention consists in a'sliding bar, with a projection and spring, arrangedwithin the keeper ot' a lock and operated by the lock-boltfor the purpose'of sounding a burglar-alarm connected with 'said -sliding bar, alias more fully hereinafter set forth.

In order to enable others skilled'in the art to which my invention appertains to make and use the same, I will uowproceed to describe its construction and operation, referring lto the annexed drawing, in which- Figure 1 is a side View ofthe lock, with the keeper broken open to show the interior arrangement of the same; and f Figure 2 is a front View ofthe keeper.

A. represents the lock, constructed in any of the known and usual ways, with an extra bolt, B, as shown.

C is the keeper of the lock, within which is an up. right bar, D, which passes through holes in the top and bottom of the keeper.

Near the-lower end of the bar D is attached an additional prong, a, which also passes through a hole in the bottom or lower end of the keeper,`to prevent the b'ar D from turning on its journals where it passes through the keeper.

Around the lower end of the bar D, between the bottom of the keeper and the shoulder formed lat the point of attachment of the prong a, is placed a spiral spring, b, which holds the bar up in proper position except when force is applied, as will be presently described, when the bar will slide downward for a certain distance.

A At such a point upon the bar D that the bolt B of the. lock will come directly above it, is placeda pro jection, E, constructed las' shownin iig. 2. The end of this projection isextended upward, as shown, the inner side of this extension beveled, andv the outer side straight and close up to the inner side of the keeper. The edge of the bolt B nearest to the beveled or rounded sideis also slightly rounded.

Any suitable alarm is connected with the upper end of the bar D, which has a hole for that purpose. The operationwill be readily seen. The bolt Bbcing locked, if anybody should attempt to open the door this bolt'will press against the beveled'orA rounded side ofthe projection E, forcing the bar D downward, and sound the alarm.

.As soon as the pressure is-rernoved the springb f will force-thebar D up again to its former place.

Having thus'fully described my invention,A

What I claim as new, and desire to secure by Letters Patent, isi j A 1. The sliding-bar D, provided with projection E,

prong a, and spring b, all constructed as shown andA described, and arranged within the keeper of a lock, substantially as and for the purposes herein set forth.

2. The combination of the keeperC, bar' D, with projection E, and the bolt B of a lock, all constructed and arranged to operate in connection with aburglaralarm, substantially as and for the purposes herein set forth.

In testimony that I claim the foregoing I have hereunto set my hand this 15th day of December, 1870.

Witnesses: JAMES HARRY THORP. Y

' GEORGE Bosman,

J. M. BRUMAGHEIM. 

